Add potatoes to a large stock pot and cover with water, bring to a boil. Once the potatoes are boiling, reduce the heat to medium low and cover. Cook for 30-40 minutes or until a knife doesn’t meet resistance when inserted.
Drain the potatoes and pass through a potato ricer or mash with a potato masher.
Stir in the salt, melted butter, heavy cream, sour cream and grated parmesan. Cover and set a side.
For the beef and vegetable mixture:
Preheat the oven to 425℉ (220℃) and prepare a 9×13 baking dish with non-stick cooking spray.
Heat a large non-stick skillet over high. When hot, add the olive oil and ground beef, break apart while cooking. Cook until browned and most of the liquid has evaporated, about 8 minutes.
To the pan, add the onion and garlic. Stir to combine, and cook for 3-4 minutes or until the onion has begun to soften. Add in the wine to deglaze the pan, scraping up any browned bits on the bottom of the pan.
Stir in worcestershire sauce, tomato paste, salt, black pepper, fresh thyme and flour. Cook and stir until well combined. Pour in the beef stock, stir and bring to a simmer. Lower the heat to medium low, and simmer until the sauce reduces by about half, about 10 minutes.
Remove the pan from heat and stir in the mixed vegetables. Add the beef and vegetable mixture to the prepared baking dish. Smooth into an even layer. Spoon the mashed potatoes over top and spread into an even layer. Use a spoon or small rubber spatula to “rough up” the top of the potatoes. This creates a texture that will crisp up in the oven as it bakes. Sprinkle the remaining 1 tablespoon of parmesan cheese over top of the mashed potatoes.
Place the baking dish on a sheet tray and bake in the preheated oven for 25 minutes. After 25 minutes, move the dish under a high broiler for 1-2 minutes or until the top is golden and crispy.
Allow the shepards pie to cool on a cooking rack for at least 25 minutes before serving. Garnish with fresh parsley and enjoy!.